A continuing concern of the sequential view, to identify the conditions under which memories and traces of reward events come to regulate instrumental behavior, is amply represented in each of the five general areas of research described in this proposal. In relation to our previous work, however, certain newer emphases are to be found in this proposal. As one example, in Section 6, which deals with the effects of intertrial interval on learning and performance, research is proposed which deals with the influence not merely of memories and traces, but of certain other classes of cues associated with intertrial interval as well. More importantly, however, by replacing the reinforcement principle formerly employed by the sequential view by what is called the reinforcement level principle, the sequential view is transformed in a rather significant way. On the one hand, certain problems already considered adequately explained in sequential terms such as negative contrast effects are now seen as involving still additional processes. On the other hand, a number of problem areas which were nor formerly explained in sequential terms, such as overtraining effects of various sorts, the effects on extinction of employing two or more different reward schedules in combination, positive contrast effects and so on, are dealt with in this proposal.